Advances in technology have enabled the introduction of mobile devices that have feature an ever increasing set of capabilities. Smartphones, for example, now offer sophisticated computing and sensing resources together with expanded communication functionality. Likewise, tablets, wearables, media players and other similar devices have shared in this progress. Notably, it is desirable and increasing common to provide a mobile device with digital imaging functions. However, although any camera may be subject to blurring as a consequence of movement when the image is being captured, implementations in a mobile device may be particularly susceptible due to consumer demand for such cameras to be smaller, cheaper and higher in resolution. A camera incorporated into a mobile device is often hand held during use and, despite efforts to be still during image recording, shaking inevitably occurs. Further, providing for increased exposure times is generally desirable, but tends to exacerbate the effects of shaking as well.
An effective technique for minimizing blur in a digital image is optical image stabilization (OIS). Such systems sense motion associated with hand shake and provoke a compensating motion in either the camera lens or the image sensor to reduce blur. As will be appreciated by those of skill in the art, using OIS may provide significantly improved image quality, particularly at higher resolutions, longer exposure times or when employing an optical zoom.
Despite these advantages, OIS systems may require significant hardware and processing resources. To facilitate incorporation into a mobile device, a digital camera featuring OIS may be integrated as a single unit. Generally, such systems include the motion sensor, which may be a two axis gyroscope, sensor processing to determine compensatory motion in response to the sensed motion, actuators to provide the compensatory motion in the image sensor or lens, and position sensors to determine whether the actuators have produced the desired movement.
Further, a conventionally integrated camera and OIS system may require relatively expensive and time consuming calibration. For example, each camera unit may be subjected to test vibrations during the manufacturing process in order to correct for mounting errors, gain errors and/or cross axis errors.
It is also noted that a typical manufacturing process for a digital camera involves cleaning the lens ultrasonically. Technologies used to implement the motion sensor for an OIS system, such as a microelectromechanical systems (MEMS) fabrication, may be damaged by the cleaning process. Accordingly, additional care and costs are associated with the manufacture of camera units featuring completely integrated OIS systems.
In light of the above, it would be desirable to facilitate the incorporation of a digital camera having OIS capabilities into a mobile device. Likewise, it would be desirable to do so while reducing the cost and complexity of a camera unit. Still further, it would be desirable to reduce the burden of manufacturing and calibrating such mobile devices. As will be described in detail below, the techniques of this disclosure satisfy these and other needs.